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Effects of Several Sulfa- Compounds on Nuclear and Cell Division
Thomas C. Fuller
Vol. 109, No. 2 (Dec., 1947), pp. 177-183
Published by: The University of Chicago Press
Stable URL: http://www.jstor.org/stable/2472609
Page Count: 7
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1. Onion roots approximately 1 inch long were immersed in solutions of 0.5% sulfanilamide and of 0.1% in tap water of the following sulfa- compounds: sulfadiazine, sulfaguanidine, sulfamerazine, sulfapyridine, and sulfathiazole. These solutions were at or slightly above the maximum solubility of these compounds in water at 20⚬ C. The solutions were changed every 24 hours, as were the controls in tap water, Fixations of the roots were made after 6, 12, 24, 48, 72, and 96 hours of treatment. Some bulbs from each series were returned to tap water after 48 hours and others after 96 hours. 2. There was immediate cessation of visible root elongation in all the treatments, but approximately half the roots of the bulbs treated with sulfanilamide developed tumors within 48 hours, owing to enlargement of the cortical cells in the region of elongation. In only one other treatment were such tumors formed on about half the roots of one bulb immersed in sulfapyridine. 3. In roots treated with sulfanilamide normal-appearing mitosis continued in a small number of the cells of the cortex and apical meristem throughout the 96 hours period of treatment. The duration of the mitotic process seemed to be materially lengthened. Disruption of the spindle mechanism and delay in the separation of the centromeres of the chromoseines were observed. As a result of the inhibition of the spindle mechanism, reversion stages occurred which resulted in the return of the anaphase chromosomes to the metabolic condition without completion of the mitotic cycle and in the production of tetraploid metaphase and anaphase figures within 96 hours after application of sulfanilamide. In no case, however, was a tetraploid cell found in division after normal growth had been resumed in tap water. Binucleate cells, resulting from the failure of the formation of the cell plate, were observed after 48 hours of treatment. The nuclei of the cortical cells in the enlarged regions appeared, normal in most cells, although some nuclei were much larger than others and than those of the controls. These large nuclei were probably tetraploid. A few other nuclei showed irregular, lobed outlines. No micronuclei were found, in contrast to the report of PETERS. The only polyploidy observed was tetraploidy. 4. Mitosis was completely blocked at 48 hours in one series of treatments with sulfanilamide. In these roots no mitotic activity and no characteristic tumor formation occurred. 5. The other five sulfa- compounds induced essentially the same responses in all the roots. Although there was no visible elongation, mitosis nevertheless continued at a slow rate throughout the 96 hours of treatment. Even though the chromosomes were shorter than in the controls, the degree of contraction, was not so great as had occurred in cells treated with sulfanilamide. On returns to tap water all treated roots resumed normal growth. 6. The markedly different responses to sulfanilamide and to the other sulfacompounds occur possibly because of the greater solubility in water of sulfanilamide than of the others.
Botanical Gazette © 1947 The University of Chicago Press